1. Field of the Invention
The present invention relates to a high-strength race which has superior rolling fatigue properties, high anti-surface fatigue strength and is superior in productivity and to a method of producing the race.
2. Description of the Related Art
There has been an increasing need for vehicles to attain low fuel consumption and low pollution from the standpoint of environmental safeguard in recent years. As one of measures to decrease fuel consumption and exhaust gas, it is effective to make a car body light-weight. Therefore, attempts are being made to develop various small-sized and light-weight structural parts of car bodies.
When vehicles to which a small-sized and light-weight drive shaft is applied are used, some cases are known where flaking and pitching of an outer race occur at the relatively early stage and therefore the life of the outer race comes to an end. It has been required for the outer race to possess high impact properties to ensure safety. Further, there is an increasing need to extend the life span of the outer race to cope with the development of outer races reduced in size. For technologies used to extend the life span of the outer race, complex heat treatment in which induction hardening is carried out after nitration is proposed in the publication of Japanese Patent Application Laid-open No. 6-173967.